A nurse is caring for a client who is on warfarin therapy for atrial fibrillation. The client's INR is 5.2. Which of the following medications should the nurse prepare to administer?

Rationale: A. Atropine is a parasympatholytic medication used to increase heart rate in cases of bradycardia by inhibiting vagal stimulation. It has no effect on coagulation pathways and therefore does not reverse the anticoagulant effects of warfarin. B. Epinephrine is a sympathomimetic used primarily in cardiac arrest, anaphylaxis, or severe hypotension. While it affects heart rate and vascular tone, it does not interact with the coagulation cascade or reduce an elevated INR. C. Protamine sulfate is the specific antidote for heparin therapy. It binds to heparin to neutralize its anticoagulant effect but is ineffective against vitamin K antagonists such as warfarin. Administering protamine would not correct the patient’s supratherapeutic INR. D. Vitamin K (phytonadione) is the antidote for warfarin. Warfarin inhibits the vitamin K–dependent synthesis of clotting factors II, VII, IX, and X. An elevated INR of 5.2 indicates that the client is at high risk for spontaneous bleeding. Administering vitamin K helps restore the synthesis of functional clotting factors, thereby reducing bleeding risk. The dose and route (oral vs. IV) depend on the severity of the INR elevation and presence of active bleeding.